Abstract: A new method for extracting the bound residue (BR) derived from
^{14}C-labeled chlorsulfuron in soils was developed, and the
technique of combining LC-MS with isotope tracing method was subsequently
applied to identify the composition of the ^{14}C-BR in a
loamy Fluvent derived from marine deposit. The results showed that the
^{14}C-[2-amino-4-methoxyl-6-methyl-1,3,5]-triazine,
^{14{C-[2-amino-4-hydroxyl-6-methyl-1,3,5]-triazine and
^{14}C-chlorsulfuron parent compound constituted the main
composition of the ^{14}C-BR derived from
^{14}C-labeled chlorsulfuron in the soil. The radioactive
ratio of three compounds accounted for 39.8%, 35.4% and 17.9% of total
recovered radioactivity, respectively. However, a small amount (3.6% of total
recovered radioactivity) of the complex of
^{14}C-[2-amino-4-hydroxyl-6-methyl-1,3,5]-triazine might
have existed in the ^{14}C-BR in association with an unknown
soil substrate. 2-chlorobenzenesulfonamide was also detected to be one of the
components of the BR. The results could well explain the mechanism of
phytotoxicity caused by the BR derived from chlorsulfuron in soil. In addition,
the mechanism of BR formation in soil was also discussed in details.
